What might these resistors and caps do in this schematic please?
In this schematic of a 136kHz Class D amplifier, do C1 and C2 with their associated 15k resistors add some sort of delay or what? Thanks
In this schematic of a 136kHz Class D amplifier, do C1 and C2 with their associated 15k resistors add some sort of delay or what? Thanks
Those look nothing more than a means of being able to tie the 2110 input to ground in the absence of any data from the 7474 flip flop. It just allows AC coupling of the flipflop outputs
In other words if the 2X frequency input has no signal then the 2110 inputs both get pulled low. Otherwise one would be high and one low which may be a non valid state for the circuit configuration.
That's my take on it anyway 🙂
In other words if the 2X frequency input has no signal then the 2110 inputs both get pulled low. Otherwise one would be high and one low which may be a non valid state for the circuit configuration.
That's my take on it anyway 🙂
Yes, as Mooly said, the caps blocks the DC if any of the outputs of the '74 is high (Always one of then is on), if not the case, the MOSFET is blown.
Thanks for the replies, and sorry for the tardy reply. I had been told they were an RC delay and helped ensure at changeover there was a delay to make sure both FET's could not conduct, however briefly. I appreciate one output from the flip flop stays high when no signal is present, and the caps are a DC block. Most similar circuits have them between the FET driver IC and the gates, this looks a bit different. Any way they could act as an RC delay? Thanks again!
this does not look like a class-d amp for me at all.
There is a "rf-output" - nothing you will find at an audio amp.
Yes, I said in my first post it's RF on 136kHz, and Class D, but very similar to a Class D audio amp.
C1, C2 and the 15K resistors form a first-order high-pass filters with a cut-off at 10KHz (15uS time constant). This means that the duty cycle of the output transistors is pretty close to 50%. The 10 ohm resistor and 1N4148 should make turn-off slightly faster than turn on to minimise cross-conduction. Most class-D RF amplifiers use less than 50% duty cycle to increase efficiency. You could try this by reducing the value of C1 & C2.
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